r263299 - Add fix-it for format-security warnings.

Bob Wilson via cfe-commits cfe-commits at lists.llvm.org
Fri Mar 11 16:14:18 PST 2016


I’m not sure how to interpret that. It says: "Clang must recover from errors as if the fix-it had been applied.” I suppose that format-security could be an error if you’re building with -Werror, but I had been interpreting that to mean an error that would block further compilation. Can someone clarify this expectation?

I don’t think we can change -Wformat-security to be a note. It is an existing warning, and people expect us to match GCC on it as well.

> On Mar 11, 2016, at 4:03 PM, Nico Weber <thakis at chromium.org> wrote:
> 
> I think http://clang.llvm.org/docs/InternalsManual.html#fix-it-hints <http://clang.llvm.org/docs/InternalsManual.html#fix-it-hints> says that if a fixit is on a warning, then clang should process the code as if the fixit had been applied. That's not the case here, so I think the fixit should be on a note instead.
> 
> On Fri, Mar 11, 2016 at 4:55 PM, Bob Wilson via cfe-commits <cfe-commits at lists.llvm.org <mailto:cfe-commits at lists.llvm.org>> wrote:
> Author: bwilson
> Date: Fri Mar 11 15:55:37 2016
> New Revision: 263299
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=263299&view=rev <http://llvm.org/viewvc/llvm-project?rev=263299&view=rev>
> Log:
> Add fix-it for format-security warnings.
> 
> Added:
>     cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m
> Modified:
>     cfe/trunk/lib/Sema/SemaChecking.cpp
>     cfe/trunk/test/Sema/format-strings-fixit.c
> 
> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=263299&r1=263298&r2=263299&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=263299&r1=263298&r2=263299&view=diff>
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Mar 11 15:55:37 2016
> @@ -3621,20 +3621,32 @@ bool Sema::CheckFormatArguments(ArrayRef
>    // format is either NSString or CFString. This is a hack to prevent
>    // diag when using the NSLocalizedString and CFCopyLocalizedString macros
>    // which are usually used in place of NS and CF string literals.
> -  if (Type == FST_NSString &&
> -      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
> +  SourceLocation FormatLoc = Args[format_idx]->getLocStart();
> +  if (Type == FST_NSString && SourceMgr.isInSystemMacro(FormatLoc))
>      return false;
> 
>    // If there are no arguments specified, warn with -Wformat-security, otherwise
>    // warn only with -Wformat-nonliteral.
> -  if (Args.size() == firstDataArg)
> -    Diag(Args[format_idx]->getLocStart(),
> -         diag::warn_format_nonliteral_noargs)
> +  if (Args.size() == firstDataArg) {
> +    const SemaDiagnosticBuilder &D =
> +      Diag(FormatLoc, diag::warn_format_nonliteral_noargs);
> +    switch (Type) {
> +    default:
> +      D << OrigFormatExpr->getSourceRange();
> +      break;
> +    case FST_Kprintf:
> +    case FST_FreeBSDKPrintf:
> +    case FST_Printf:
> +      D << FixItHint::CreateInsertion(FormatLoc, "\"%s\", ");
> +      break;
> +    case FST_NSString:
> +      D << FixItHint::CreateInsertion(FormatLoc, "@\"%@\", ");
> +      break;
> +    }
> +  } else {
> +    Diag(FormatLoc, diag::warn_format_nonliteral)
>        << OrigFormatExpr->getSourceRange();
> -  else
> -    Diag(Args[format_idx]->getLocStart(),
> -         diag::warn_format_nonliteral)
> -           << OrigFormatExpr->getSourceRange();
> +  }
>    return false;
>  }
> 
> 
> Modified: cfe/trunk/test/Sema/format-strings-fixit.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/format-strings-fixit.c?rev=263299&r1=263298&r2=263299&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/format-strings-fixit.c?rev=263299&r1=263298&r2=263299&view=diff>
> ==============================================================================
> --- cfe/trunk/test/Sema/format-strings-fixit.c (original)
> +++ cfe/trunk/test/Sema/format-strings-fixit.c Fri Mar 11 15:55:37 2016
> @@ -16,6 +16,8 @@ typedef __UINTMAX_TYPE__ uintmax_t;
>  typedef __PTRDIFF_TYPE__ ptrdiff_t;
>  typedef __WCHAR_TYPE__ wchar_t;
> 
> +extern const char *NonliteralString;
> +
>  void test() {
>    // Basic types
>    printf("%s", (int) 123);
> @@ -94,6 +96,9 @@ void test() {
>    printf("%G", (long double) 42);
>    printf("%a", (long double) 42);
>    printf("%A", (long double) 42);
> +
> +  // nonliteral format
> +  printf(NonliteralString);
>  }
> 
>  int scanf(char const *, ...);
> @@ -218,6 +223,7 @@ void test2(int intSAParm[static 2]) {
>  // CHECK: printf("%LG", (long double) 42);
>  // CHECK: printf("%La", (long double) 42);
>  // CHECK: printf("%LA", (long double) 42);
> +// CHECK: printf("%s", NonliteralString);
> 
>  // CHECK: scanf("%99s", str);
>  // CHECK: scanf("%s", vstr);
> 
> Added: cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m?rev=263299&view=auto <http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m?rev=263299&view=auto>
> ==============================================================================
> --- cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m (added)
> +++ cfe/trunk/test/SemaObjC/format-strings-objc-fixit.m Fri Mar 11 15:55:37 2016
> @@ -0,0 +1,31 @@
> +// RUN: cp %s %t
> +// RUN: %clang_cc1 -x objective-c -triple x86_64-apple-darwin -Wno-objc-root-class -pedantic -Wall -fixit %t
> +// RUN: %clang_cc1 -x objective-c -triple x86_64-apple-darwin -Wno-objc-root-class -fsyntax-only -pedantic -Wall -Werror %t
> +// RUN: %clang_cc1 -x objective-c -triple x86_64-apple-darwin -Wno-objc-root-class -E -o - %t | FileCheck %s
> +
> +typedef signed char BOOL;
> +typedef unsigned int NSUInteger;
> +typedef struct _NSZone NSZone;
> + at class NSCoder, NSString, NSEnumerator;
> + at protocol NSObject  - (BOOL)isEqual:(id)object; @end
> + at protocol NSCopying  - (id)copyWithZone:(NSZone *)zone; @end
> + at protocol NSMutableCopying  - (id)mutableCopyWithZone:(NSZone *)zone; @end
> + at protocol NSCoding  - (void)encodeWithCoder:(NSCoder *)aCoder; @end
> + at interface NSObject <NSObject> {} @end
> + at interface NSString : NSObject <NSCopying, NSMutableCopying, NSCoding>  - (NSUInteger)length; @end
> +extern void NSLog(NSString *format, ...);
> +
> +/* This is a test of the various code modification hints that are
> +   provided as part of warning or extension diagnostics. All of the
> +   warnings will be fixed by -fixit, and the resulting file should
> +   compile cleanly with -Werror -pedantic. */
> +
> +extern NSString *NonliteralString;
> +
> +void test() {
> +  // nonliteral format
> +  NSLog(NonliteralString);
> +}
> +
> +// Validate the fixes.
> +// CHECK: NSLog(@"%@", NonliteralString);
> 
> 
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